implement repo.logo and repo.logo-link

Allow for per repo logo and logo-link; Use global logo and logo-link per
default.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgitrc.5.txt

@@ -370,6 +370,15 @@ repo.enable-subject-links::
 	A flag which can be used to override the global setting
 	`enable-subject-links'. Default value: none.
 
+repo.logo::
+	Url which specifies the source of an image which will be used as a logo
+	on this repo's pages. Default value: global logo.
+
+repo.logo-link::
+	Url loaded when clicking on the cgit logo image. If unspecified the
+	calculated url of the repository index page will be used. Default
+	value: global logo-link.
+
 repo.max-stats::
 	Override the default maximum statistics period. Valid values are equal
 	to the values specified for the global "max-stats" setting. Default